Semiconductor device and method for fabricating the device

Abstract

A first gate electrode for an n-channel MOSFET includes first and second metal films and a low-resistivity metal film. The first metal film has been deposited on a first gate insulating film and is made of a first metal having a work function located closer to the conduction band of silicon with reference to an intermediate level of silicon bandgap. The second metal film has been deposited on the first metal film and is made of a second metal having a work function located closer to the valence band of silicon with reference to the intermediate level of silicon bandgap. The low-resistivity metal film has been deposited on the second metal film. A second gate electrode for a p-channel MOSFET includes: the second metal film, which has been deposited on a second gate insulating film and is made of the second metal; and the low-resistivity metal film deposited on the second metal film.

What is claimed is:  
     
       1. A semiconductor device comprising 
       an n-channel MOSFET including: a first gate insulating film; and a first gate electrode formed on the first gate insulating film, where the first gate insulating film is deposited on the bottom of a first recessed groove that has been provided for forming the first gate electrode in a dielectric film deposited on a silicon substrate, and  
       a p-channel MOSFET including: a second gate insulating film; and a second gate electrode formed on the second gate insulating film, where the second gate insulating film is deposited on the bottom of a second recessed groove that has been provided for forming the second gate electrode in the dielectric film,  
       wherein the first gate electrode includes:  
       a first metal film, which has been deposited on the first gate insulating film, is made of a first metal or a compound thereof and has a first recess inside the first recessed groove, the first metal having a work function located closer to the conduction band of silicon with reference to an intermediate level of silicon bandgap;  
       a second metal film, which has been deposited on the first metal film, is made of a second metal or a compound thereof and has a second recess inside the first recess, the second metal having a work function located closer to the valence band of silicon with reference to the intermediate level of silicon bandgap; and  
       a first low-resistivity metal film, which is made of a low-resistivity metal and with which the second recess has been filled, and  
       wherein the second gate electrode includes:  
       a third metal film, which has been deposited on the second gate insulating film, is made of the second metal or the compound thereof and has a third recess inside the second recessed groove; and  
       a second low-resistivity metal film, which is made of the low-resistivity metal and with which the third recess has been filled.  
     
     
       2. The device of  claim 1 , wherein the first metal is selected from the group consisting of Zr, Nb, Ta, Mo, V, Ti, Hf, Al and TaN, and 
       wherein the second metal is selected from the group consisting of Pt, Ir, Re, RuO 2 , Ni and Co.  
     
     
       3. A semiconductor device comprising 
       an n-channel MOSFET including: a first gate insulating film; and a first gate electrode formed on the first gate insulating film, where the first gate insulating film is deposited on the bottom of a first recessed groove that has been provided for forming the first gate electrode in a dielectric film deposited on a silicon substrate, and  
       a p-channel MOSFET including: a second gate insulating film; and a second gate electrode formed on the second gate insulating film, where the second gate insulating film is deposited on the bottom of a second recessed groove that has been provided for forming the second gate electrode in the dielectric film,  
       wherein the second gate electrode includes:  
       a first metal film, which has been deposited on the second gate insulating film, is made of a first metal or a compound thereof and has a first recess inside the second recessed groove, the first metal having a work function located closer to the valence band of silicon with reference to an intermediate level of silicon bandgap;  
       a second metal film, which has been deposited on the first metal film, is made of a second metal or a compound thereof and has a second recess inside the first recess, the second metal having a work function located closer to the conduction band of silicon with reference to the intermediate level of silicon bandgap; and  
       a first low-resistivity metal film, which is made of a low-resistivity metal and with which the second recess has been filled, and  
       wherein the first gate electrode includes:  
       a third metal film, which has been deposited on the first gate insulating film, is made of the second metal or the compound thereof and has a third recess inside the first recessed groove; and  
       a second low-resistivity metal film, which is made of the low-resistivity metal and with which the third recess has been filled.  
     
     
       4. The device of  claim 3 , wherein the first metal is selected from the group consisting of Pt, Ir, Re, RuO 2 , Ni and Co, and 
       wherein the second metal is selected from the group consisting of Zr, Nb, Ta, Mo, V, Ti, Hf, Al and TaN.  
     
     
       5. A semiconductor device comprising 
       an n-channel MOSFET including: a first gate insulating film; and a first gate electrode formed on the first gate insulating film, where the first gate insulating film is deposited on the bottom of a first recessed groove that has been provided for forming the first gate electrode in a dielectric film deposited on a silicon substrate, and  
       a p-channel MOSFET including: a second gate insulating film; and a second gate electrode formed on the second gate insulating film, where the second gate insulating film is deposited on the bottom of a second recessed groove that has been provided for forming the second gate electrode in the dielectric film,  
       wherein the first gate electrode includes:  
       a metal film, which has been deposited on the first gate insulating film, is made of a first metal or a compound thereof and has a recess inside the first recessed groove, the first metal having a work function located closer to the conduction band of silicon with reference to an intermediate level of silicon bandgap; and  
       a first low-resistivity metal film, with which the recess is filled and which is made of a second metal or a compound thereof, the second metal being a low-resistivity metal having a work function located closer to the valence band of silicon with reference to the intermediate level of silicon bandgap, and  
       wherein the second gate electrode includes  
       a second low-resistivity metal film, which has been deposited on the second gate insulating film to fill the second recessed groove and is made of the second metal or the compound thereof.  
     
     
       6. The device of  claim 5 , wherein the first metal is selected from the group consisting of Zr, Nb, Ta, Mo, V, Ti, Hf, Al and TaN, and 
       wherein the second metal is selected from the group consisting of Pt, Ir, Ni and Co.  
     
     
       7. A semiconductor device comprising 
       an n-channel MOSFET including: a first gate insulating film; and a first gate electrode formed on the first gate insulating film, where the first gate insulating film is deposited on the bottom of a first recessed groove that has been provided for forming the first gate electrode in a dielectric film deposited on a silicon substrate, and  
       a p-channel MOSFET including: a second gate insulating film; and a second gate electrode formed on the second gate insulating film, where the second gate insulating film is deposited on the bottom of a second recessed groove that has been provided for forming the second gate electrode in the dielectric film,  
       wherein the second gate electrode includes:  
       a metal film, which has been deposited on the second gate insulating film, is made of a first metal or a compound thereof and has a recess inside the second recessed groove, the first metal having a work function located closer to the valence band of silicon with reference to an intermediate level of silicon bandgap; and  
       a first low-resistivity metal film, with which the recess is filled and which is made of a second metal or a compound thereof, the second metal being a low-resistivity metal having a work function located closer to the conduction band of silicon with reference to the intermediate level of silicon bandgap, and  
       wherein the first gate electrode includes  
       a second low-resistivity metal film, which has been deposited on the first gate insulating film to fill the first recessed groove and is made of the second metal or the compound thereof.  
     
     
       8. The device of  claim 7 , wherein the first metal is selected from the group consisting of Pt, Ir, Re, RuO 2 , Ni and Co, and 
       wherein the second metal is selected from the group consisting of Zr, Mo and Al.  
     
     
       9. A semiconductor device comprising 
       an n-channel MOSFET including: a first gate insulating film; and a first gate electrode formed on the first gate insulating film, where the first gate insulating film is deposited on the bottom of a first recessed groove that has been provided for forming the first gate electrode in a dielectric film deposited on a silicon substrate, and  
       a p-channel MOSFET including: a second gate insulating film; and a second gate electrode formed on the second gate insulating film, where the second gate insulating film is deposited on the bottom of a second recessed groove that has been provided for forming the second gate electrode in the dielectric film,  
       wherein the first gate electrode includes:  
       a first metal film, which has been deposited on the first gate insulating film, is made of a first metal or a compound thereof and has a first recess inside the first recessed groove, the first metal having a work function located closer to the conduction band of silicon with reference to an intermediate level of silicon bandgap; and  
       a first low-resistivity metal film, with which the first recess is filled and which is made of a low-resistivity metal, and  
       wherein the second gate electrode includes:  
       a second metal film, which has been deposited on the second gate insulating film, is made of a second metal or a compound thereof and has a second recess inside the second recessed groove, the second metal having a work function located closer to the valence band of silicon with reference to the intermediate level of silicon bandgap; and  
       a second low-resistivity metal film, with which the second recess is filled and which is made of the low-resistivity metal.  
     
     
       10. The device of  claim 9 , wherein the first metal is selected from the group consisting of Zr, Nb, Ta, Mo, V, Ti, Hf, Al and TaN, and 
       wherein the second metal is selected from the group consisting of Pt, Ir, Re, RuO 2 , Ni and Co.